This disclosure relates generally to methods and apparatus for generating vibrations or fluid pulses with a downhole tool. More specifically, this disclosure relates to methods and apparatus that enable a downhole pulse generating device to generate pulses at a variety of frequencies and amplitudes.
Downhole pulse generating devices are used to create fluctuations in fluid pressure that create vibrations in the drill string. The vibrations or pulses can help prevent the build-up of solid materials around the drill string, which can reduce friction and prevent the drill string from becoming stuck in the well. Thus, the use of pulse generating devices can be useful in extending the operating range of drilling assemblies.
Thus, there is a continuing need in the art for methods and apparatus for generating downhole pulses that overcome these and other limitations of the prior art.